Worldbuilding isn't just one of the cool features of fantasy novels, or a secondary source of entertainment — it's the chief feature that draws people to well-built fantasy worlds, and draws so many people into the works of J.R.R. Tolkien and George R.R. Martin. That's what Throne of the Crescent Moon author Saladin Ahmed argues, in a fascinating piece for NPR:

What is it that draws millions of readers and viewers to these works? Surely, the vast casts of compelling characters and the harrowing, twist-filled plots have something to do with it. But there are other genres that scratch those itches. What is it about fantasy?

A few years ago, I was fortunate enough to attend an informal lecture/pep talk for up-and-coming fantasy writers by the man Time called "the American Tolkien," the now-world-famous Martin. The grizzled master described the very early days of Tolkien's cult popularity to a room of us wide-eyed newbies. When college students and hippies started hanging up Lord of the Rings posters, Martin pointed out, "It wasn't the book covers or some artist's conception of Frodo that went on our walls. It was the map of Middle-earth."

In other words, more than the profound lessons on the corrupting influence of power, more than the stirring battle scenes, more even than beloved characters like Frodo and Sam, readers came to Tolkien's books for the rich, magical world that they built out of his words. Martin has taken this lesson to heart in his work - as have some of his most successful contemporaries, like the late Jordan - pulling fans into constructed worlds every bit as elaborate as Tolkien's. And readers, it seems, can't get enough. Indeed, for many readers and no few writers of fantasy, world-building is the very heart of our genre.